The pregnant-again Hills alum, 26, kept it sweet and simple at the event, wearing a strapless, black, hand-beaded lace cocktail dress by Oliver Tolentino and pointed-toe pumps from her own Chinese Laundry line. "I haven’t been able to wear my really high shoes anymore," she told Us Weekly on the red carpet at Tuesday's event. "I have all these great shoes that I’ll never get to wear again."

Regarding her shoe selection for the evening, she quipped: "Luckily, all the shoes that I design aren’t as high as I used to wear, so these actually are a piece of cake for me."

The designer left her blonde locks in loose waves and kept her makeup to a minimum as she glowed in front of the cameras. She proudly cupped her growing tummy with her left hand, as her ring finger sparkled on the red carpet. "I mean of course I want a girl!" she told Us on Tuesday. (Cavallari announced in late October that she was expecting her second baby with husband Jay Cutler. The two are already parents to 15-month-old son Camden Jack.)

"But another boy would be fun, too, because then Cam would have a buddy," the star added. "I love having a boy. So I honestly don’t care." Baby Camden — whose latest milestones include walking, talking and "making animal noises, which is really funny," noted Cavallari — is "still too young" to grasp that he will be an older brother.

"I think the closer we get, the more he will understand," she added. "But he probably won’t get it until the baby’s here."

As for holiday celebrations, the reality standout told Us that she will find out the baby's gender right before Christmas: "I’m going to have my doctor write it on a note, and put it in an envelope," she shared. "And we’re going to open it on Christmas — Jay and I."

She said the surprise will remain between the couple: "Just the two of us! Jay doesn’t want to tell anybody, not even our parents!"